Device for adjusting the height of a vehicle

ABSTRACT

The present invention is a system for adjusting the height of vehicles that have coil spring suspensions. The invention may be added to existing vehicle suspensions without the need to remove and replace the existing vehicle suspension components. The invention includes cylinders, pistons, seals, dust shields, pressure pump(s) and storage tank(s). It also may optionally include electronic hardware, such as, an electronic controller and software, to control the functions of the system and sensor(s) which detect ground clearance and speed. The invention may be operated manually by a vehicle driver through push buttons, which may operate through the vehicle&#39;s existing cruise control buttons. Alternatively, the system can be automated through an electronic control unit (ECU) to avoid collision with obstacles in the vehicle&#39;s path.

This application claims the priority of U.S. provisional patentapplication No. 61/575,718 filed on Aug. 25, 2011.

FIELD OF THE INVENTION

This invention generally relates to lift systems, and more specifically,lift systems for adjusting the ground clearance of vehicles to avoidcollisions with obstacles, such as speed bumps or sloping driveways,which can scrape and damage the underbody of a vehicle.

BACKGROUND OF THE INVENTION

Motor vehicle suspension systems have an inherent problem that resultsin various compromises. Vehicle suspension systems are generallydesigned to avoid obstacles anticipated to be in the vehicle's path.Some vehicles, such as off-road vehicles, are designed with a highground clearance to avoid obstacles encountered in rugged terrain, whileother vehicles are designed with low ground clearance for high speedperformance and/or sportier appearance. Ground clearance is the amountof space between the base of an automobile tire and the underside of thevehicle; or the shortest distance between a flat, level surface, and anypart of a vehicle other than those parts designed to contact the ground(such as tires, tracks, skis, etc.). The benefits of low groundclearance and lower vehicle height are numerous and include less windresistance, better fuel economy, better acceleration, better cornering,and better braking. Another significant advantage of low groundclearance is that it allows for better aesthetics such as providing alower, sleeker, and sportier appearance that is desired by many drivers.

Many modern vehicles are designed and built with low ground clearancefor the sportier appearance. Vehicle owners also lower their vehicles,through after-market modification, for enhanced performance, fueleconomy and sportier appearance. One of the most common ways to lower avehicle is through the use of a coilover, a vehicle suspension devicethat incorporates a coil spring positioned over and around a shockabsorber shaft that is connected to a shock absorber body. Use of acoilover allows for a limited amount of height adjustment by adjustingthe height of the coil spring's lower mounting point.

Reducing a vehicle's ground clearance height frequently results inundesired contact (collisions or scraping) between the vehicle andobstacles in the vehicle's path, such as speed bumps and slopingdriveways. Unfortunately, when contact occurs, the vehicle is oftendamaged from the contact.

In the past, other vehicle lift systems have been developed, but theyfall short of providing an adequate solution for many reasons. Forexample, some lift systems are designed and built to be vehicle-specificand are not readily adaptable to other vehicles. On the other hand, liftsystems designed to fit a variety of vehicles often require the removalor replacement of existing components, resulting in added costs for thereplacement components and loss of performance from the removal ofcritical or beneficial existing components. Such removed components mayinclude coil springs, dust sleeves and bump stops.

Some prior art lift systems employ pressurized rubber air bags or airsleeves to replace coil springs in a suspension system. These systems donot retain the performance characteristics and benefits of metal coilsprings, and incur the added cost of replacing the existing shockabsorbers and/or metal coil springs with air bags or air sleeves.Moreover, components in lift systems that use metal coil springs may beso tall or thick that they do not fit into vehicles with the existingsuspension springs. In such cases, the coil springs must be replacedwith shorter springs resulting in a loss of suspension performance fromthe shorter spring.

Prior art lift systems also use hollow double-walled cylinder designshaving concentric inner and outer cylinder walls. This design iscomplicated, more costly to manufacture, and more difficult to protectagainst dust and contaminants. These systems are also less efficient inthe use of stored air pressure.

Prior art lift systems also do not typically provide dust shields (forthe inner cylinder walls, outer cylinder walls, and/or the shockabsorber shaft) to reduce contamination and wear on these surfaces andtheir seals attached thereon.

Still other prior art lift systems also have reduced pressurized surfaceareas on which the piston can act, resulting in inefficient use of powerand the need for a larger storage tank to hold the compressed air (orother fluid), which is used to lift a vehicle. The tank required mayreduce storage space, or even be so large that it cannot fit into manyvehicles in a practical manner, and therefore is not able to be used inthose vehicles.

Prior art lift systems that use bump stops, typically do so in a mannerthat reduces the effective pressurized area above the bump stop, makingthe system less efficient and requiring more air pressure and/or storedpressurized air to operate. They also do not provide a means for havingthe bump stop travel in tandem with the piston.

Prior art lift systems also do not have an adjustable, automatedactivation system that automatically senses obstacles in a vehicle'spath and raises or lowers the vehicle based on the vehicle's proximityto the obstacles and its speed.

Other lift systems use components, such as large pneumatic cylinders orlarge air tanks that are often too large to install into many vehicles.These larger components also add undesirable weight to the vehicle, thusdecreasing vehicle performance and efficiency.

Other systems that use compressed air tanks may also allow condensation(water) in the air tank to be passed through the air outlet port undercertain driving conditions, which may cause surges of the water (surgewater). Examples of such conditions include acceleration, braking andcornering. The surge water that passes through the air lines to thevalves, pressure sensors, cylinders and other components has detrimentaleffects on these components.

Some other systems use hydraulic pumps and pressurized liquid to raisethe vehicle, and use hollow double-walled cylinders having concentricinner and outer walls. This type of system is less efficient andrequires significantly higher operating pressures to be effective.Hydraulic systems also require more costly hydraulic pumps and/or tanksfilled with heavy hydraulic fluid and have the risk of fluid leaksand/or oil spills.

Hydraulic systems that have the cylinder and pistons fitted to thebottom of the spring located around the body of the shock absorber addundesirable unsprung weight to the suspension, thus reducing theperformance of the suspension.

Hydraulic systems also pump fluid only when it is needed to lift avehicle. Thus, they are slower acting systems that require strong pumpsto raise a vehicle with enough speed to be effective. This means theydraw higher amperage on a vehicle's electrical system. Further, becausehydraulic systems typically raise vehicles slowly, they are notpractical to use in many driving situations.

Prior art lift systems include: Umbrella Auto Design, Roberuta, TopSecret, Mode Parfum, Skipper, K W Hydraulic Lift System, Tech-Art, RamLift Pro, Phantom VIP, Stance-Solutions, Air Force, Air Lift, andAccuair.

It is an object of the present invention to provide an affordable liftsystem that is adaptable to a large variety of vehicles.

It is another object of the present invention to provide an efficientlift system that only requires small pressurized cylinders and storagetanks.

It is a further object of the present invention to eliminate or reducethe effects of environmental contaminants and the damage they cause tolift system components.

It is still a further object to provide means for operating the systemin safe manner that does not require the driver to take his eyes off theroad (to look for and operate switches), and to make the operation ofthe system automatic and hands-free.

It is a further object to overcome the drawbacks relating to the priorart devices discussed above and to provide at least some of the benefitsdescribed below.

DISCLOSURE OF THE INVENTION

The above and other objects are achieved by a device for lifting avehicle that has a suspension system. The suspension system comprises acoil spring and shock absorber with a shock absorber shaft and a shockabsorber body. The coil spring is coaxially coiled around the shockabsorber shaft and has a coil spring diameter. The shock absorber bodyhas a body diameter that is smaller than the coil spring diameter.

The device further preferably comprises a hollow cylinder having acylinder outer diameter larger than the coil spring diameter. Thecylinder is formed by circular cylinder top with a cylinder top rim, acentral cylinder-shaft aperture, and cylindrical cylinder side wallsconnected to, and extending downwardly from, the cylinder top rim to acylinder bottom. The cylinder top and said cylinder side walls define aninner cylinder bore. The cylinder bore has a cylinder inner diametergreater than the body diameter. An inlet port extends inwardly from thecylinder top rim into the cylinder bore. There is also an innercircumferential retaining ring groove located near the cylinder bottom.A retaining ring is also retained in the inner circumferential retainingring groove. The retaining ring creates a barrier between the pistonskirt (described below) and the cylinder side walls to preventcontaminants from entering said cylinder bore. The cylinder is sealinglycoaxially mounted onto said shock absorber shaft through acylinder-shaft seal in the cylinder-shaft aperture.

The device also comprises a cylindrical piston having a piston diameterless than the cylinder inner diameter slidable within the cylinder bore.The piston has a circular piston top with a central piston-shaftaperture and a piston top rim with an outer circumferential inlet recessat the piston top rim. A cylindrical coil spring flange extendsdownwardly from the piston top. A bump stop flange extends inwardly(toward the shock absorber shaft) from the coil spring flange. A bumpstop having one or more bump stop grooves is retained in the bump stopflange. There is also an outer circumferential piston-bore grooveparallel to, and downwardly spaced apart from, the inlet recess. Apiston skirt flange extends downwardly from the piston-bore groove. Thepiston is sealingly coaxially mounted onto the shock absorber shaftthrough said piston-shaft aperture by a piston-shaft seal in saidpiston-shaft aperture.

The device also preferably contains a substantially cylindrical pistonskirt having a skirt diameter less than the cylinder inner diameter, askirt top, and a skirt bottom, attached to the piston skirt flange atsaid skirt top. The piston skirt has a circular bottom flange attachedto the skirt bottom that extends outwardly (away from the shock absorbershaft) from the piston skirt. The skirt top is preferably taperedinwardly between the skirt top and the skirt bottom. The piston and thepiston skirt can also preferably be integrally formed instead of beingseparate components.

The piston diameter and the skirt diameter are sufficiently less thanthe cylinder inner diameter so that the piston and the piston skirt cantilt or wobble within the cylinder bore.

A piston-bore seal is also preferably retained in the piston-boregroove. The piston-bore seal preferably contains a wiper to clean thecylinder bore when the cylinder and the piston slide apart. It alsopreferably contains an over-sized upper sealing lip that extends between1 mm to 2 mm above the rest of the piston-bore seal.

The piston top, cylinder top, piston bore seal, and the cylinder sidewalls form an expandable pressure space that is in fluid communicationwith the inlet port.

The device is activated when a pressurized fluid enters through theinlet port into the expandable pressure space and causes the piston andcylinder to slide apart, thereby raising the vehicle. The device isdeactivated when the pressurized fluid exits through the inlet port fromthe expandable pressure space and causes the piston and cylinder toslide together, thereby lowering the vehicle. The pressurized fluid ispreferably pressurized air. The device also preferably comprises acylindrical dust shield that attaches to the bump stop grooves. The dustshield has a shield diameter that is greater than said body diameter.

The present invention also preferably contains an interface operablyconnected to the device that uses existing original equipmentmanufacturer cruise control switches to activate and deactivate thedevice, and an electronic control unit operably connected to the devicefor automatic sensing of the vehicle's ground clearance and speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of the present invention'scylinder and piston for adjusting the height of a vehicle, as installedover a shock absorber and coil spring.

FIG. 2 is a cross-sectional view of a first prior art device, whichcontains a hollow double-walled cylinder with concentric inner and outercylinder walls and a ring-shaped piston.

FIG. 3 is a cross-sectional view of a second prior art device.

FIG. 4 is a cross-sectional view of the present invention with thepiston tilted in an off-axis orientation relative to the cylinder(wobbling within the cylinder) as it would be during assembly of thepiston into the cylinder or disassembly of the piston out of thecylinder.

FIG. 5 is a cross-sectional view of the present invention's seal betweenthe piston and cylinder bore (piston-bore seal).

FIG. 6 is a cross-sectional view of a simple prior art piston-bore seal.

FIG. 7 is a cross-sectional view of the present invention's seal betweenthe cylinder and the shock absorber shaft (cylinder-shaft seal).

FIG. 8 is a cross-sectional view of the present invention's seal betweenthe piston and shock absorber shaft (piston-shaft seal).

FIG. 9 is a flow diagram of how the present invention operates throughthe use of an Electronic Control Unit (ECU) and other controls.

FIG. 10 is a longitudinal cross-sectional view of an alternate presentlypreferred embodiment of the invention.

FIG. 11 is a longitudinal cross-sectional view of another alternatepresently preferred embodiment of the invention.

DESCRIPTION OF A PRESENTLY PREFERRED EMBODIMENT

Referring to FIG. 1, shown is a longitudinal cross-sectional view of thepresently preferred embodiment of the invention comprising a liftingdevice that is placed on a vehicle's shock absorber shaft S and coilspring C, but beneath the vehicle's chassis (or body). The circular topof the hollow cylinder rests against the vehicle's underbody (orchassis) to support the weight of the vehicle. A piston 32 is positionedinside the cylinder 22 and is proportioned for travel within thecylinder bore 18. The piston 32 is situated at the top of the coilspring C. The weight of the vehicle is supported by this coil spring Cthrough the springs' contact with the pistons' spring perch section 36.The cylinder 22, piston 32, rubber or plastic bump stop 10, and dustshield 11 are coaxial with the shock absorber shaft S passing throughthe center of the cylinder 22, piston 32, rubber or plastic bump stop10, and dust shield 11.

The cylinder 22 has circular cylinder top. There is an aperture at thecenter of the cylinder top (cylinder-shaft aperture) to allow passage ofa shock absorber shaft S. The cylinder has a cylinder-shaft seal 28 thatforms an air-tight seal between the cylinder 22 and the shock absorbershaft S. It also has an inlet port 14 for the passage of pressurizedfluids or gasses into and out of the cylinder 22 for activation anddeactivation the lift system. The cylinder 22 is hollow and has a singlewall, with an outer cylinder wall surface 16 and an inner cylinder wallsurface (or cylinder bore) 18.

The piston 32 rests inside the hollow cylinder 22 (when the lift systemis deactivated) and is proportioned for travel within the cylinder bore18. The piston 32 may be constructed of metal, plastic or any othersuitable materials. It has a piston to shaft seal (piston-shaft seal) 38that forms an air-tight seal between the piston 32 and the shockabsorber shaft S. It also has a piston skirt (or skirt) 62 that limitsthe pivoting of the piston when it is installed in the cylinder 22. Thetop of the piston skirt 62 contains a tapered section 56, which aids inthe alignment of the piston 32 with the center of the cylinder 22through the tapered section's contact with a retaining ring 72 when thepiston is fully extended (activated). Likewise, the bottom of the pistonskirt 62 has an outwardly tapered section 58 that also aids in thealignment of the piston 32 with the center of the cylinder 22 when thepiston is fully retracted (deactivated). These features assist inkeeping the axis of the piston in alignment with the axis of thecylinder when the piston is extended or retracted, and they help toeliminate the need to use the cylinder bore 18 to facilitate alignment.This means there is less wear on the cylinder bore 18 over the lifetimeof the device.

The piston skirt 62 preferably has a circumference that is large enoughkeep the piston 32 in alignment with the cylinder 22 and small enough toallow the installation of the retaining ring 72 when the piston isinstalled in the cylinder. Preferably, the diameter of the piston skirt(skirt diameter) 62 is no larger than the cylinder bore 18, minus twotimes the width of the retaining ring's 72 radial wall thickness, minusthe depth of the retaining ring groove 20 in the cylinder. The pistonskirt preferably does not come into contact with, or wear upon, thecylinder bore 18. The piston skirt preferably only comes into contactwith the retaining ring 72, which is a durable component and is not asealing surface. By eliminating contact of the piston with the cylinderbore 18 (the inner wall of the cylinder), the wear upon the cylinderbore is greatly reduced and the life of the cylinder's bore 18 and thepiston to bore seal (piston-bore seal) 40 are greatly improved.

The piston skirt 62 preferably has an unconventionally large gap betweenthe skirt and the cylinder bore 18. The large gap (illustrated in FIG.4) allows the piston 32 to be installed into the cylinder 22 in a highlypivoted orientation, which in turn allows for the use of seals withcomplex designs, such as highly compliant, over-sized sealing lips 41and wiper feature (wiper) 42, as illustrated in FIG. 5, in the preferreddevice. These types of seals cannot be used in systems that restrictwobbling (tilting or canting) of the piston 32 during assembly becausethe wiper feature 42 and the sealing lip 41 would become lodged in theretaining ring groove 20, if the piston 32 entered or exited thecylinder 22 with the seals parallel to the groove as is done in theprior art. Wipers 42 are desirable because they wipe contaminants fromthe surface of the cylinder bore 18 every time the piston 32 isactivated and travels downward in the cylinder 22, specifically thecylinder bore 18.

The piston skirt 62 may be integrated with the rest of the piston as asingle piece, or it may be a separate modular component that can beattached to the piston 32 (at a piston skirt flange extending downwardlyfrom the piston-bore groove 35) using conventional methods, such as apress fit or friction fit. By using a separate modular attachable pistonskirt, different lengths of the piston skirt can adjust the total lengthof the piston 32 can be adjusted to accommodate various lengths oftravel of the piston (or piston strokes) that may be desirable inconjunction with cylinders of various lengths.

In another preferred embodiment of the invention, the piston 32 has aremovable piston skirt 62 that allows the piston to be rotated 360degrees within the cylinder 22 during assembly. The skirt 62 may beattached to the piston after the piston has been inserted into thecylinder. This is not possible in the prior art devices shown in FIGS. 2and 3. By employing removable piston skirt(s) that allow extensiverotation of the piston within the cylinder during assembly, an evenwider range of seals and wipers may be used with the benefits that comewith those seals and wipers. Additionally, by employing the use ofremovable piston skirts, the overall length of the piston can easily bealtered to match the lengths of various cylinders, thus enabling thepiston to have effective strokes of various lengths that may bedesirable for various vehicles or various applications.

Preferably, the piston 32 also has two flanges. A circular bottom flange64 extending outwardly from the bottom of the piston skirt 62 providesadded strength and rigidity to the skirt. This circular bottom flange 64and the piston skirt 62 work in conjunction with the retaining ring 72to keep the piston in proper alignment relative to the cylinder 22,while the piston 32 is extending or retracting within the cylinder 22.These components also serve as a system to shield the cylinder bore 18from dust and other contaminants, to reduce wear and improve the life ofthe cylinder bore 18, the piston-bore seal 40, and the piston skirt 62.

The piston 32 preferably also has a coil spring flange 46 extendingdownwardly from the piston top to retain the coil spring C in the properposition within the piston. This coil spring flange 46 also has a bumpstop flange 48 extending inwardly toward the shock absorber shaft toretain an elastomeric bump stop 10. The bump stop does not contact theshock absorber shaft S. This positioning of the bump stop enables it tomove in tandem with the piston 32 and the top of the coil spring C asthe piston is activated and deactivated. This arrangement also allowsthe bump stop 10 to travel downward and upward over the shock absorbershaft S without any friction or wear on the shock absorber shaft,reducing wear on the shaft, unlike in the prior art.

The bump stop 10 preferably has one or more grooves (bump stop grooves)9 in its outer circumference to secure a dust shield (or dust sleeve)11. The dust sleeve 11 follows the travel of the piston 32 and bump stop10 and maintains its position relative to the top of the coil spring C.This dust shield 11 protects the shock absorber shaft S and the shockabsorber shaft seals 28,38 from contaminants such as dust, water andsalt, which can lead to deterioration of these components.

In the presently preferred embodiment of the invention, the piston 32has a circumferential groove (piston-bore groove) 35 that retains apiston-bore seal 40 to form an airtight seal between the piston 32 andcylinder bore 18. The piston-bore seal 40 may be located at the samelevel as the spring perch 36, or at a level that is higher or lower thanthe spring perch 36. The spring perch 36 rests on the top of the coilspring C. Ideally, the spring perch 36 is located as high as possible tominimize the height of the piston 32 that is situated on the top of thecoil spring C.

The top of the piston preferably also has a reduced diameter relative tothe rest of the piston due to an outer circumferential inlet recess 34that circles the top of the piston. The reduced dimension of the top ofthe piston provides several significant benefits.

The circumferential inlet recess 34 allows the piston to travel withinthe cylinder 22 without interfering with any fitting installed into theinlet port 14 when the fitting extends inward beyond the cylinder bore18. This helps to minimize the added height to the top of the coilspring C compared to lift systems in the prior art and it also permitsthe use of a cylinder 22 with a smaller outer diameter to fit invehicles with space limitations.

The circumferential inlet recess 34 also facilitates the inrush of apressurized fluid into the cylinder 22 through the inlet port 14 forfaster lifting of a vehicle due to the reduced diameter and heightdimensions of the piston top. The presently preferred embodiment of theinvention uses compressed air, however, other pressurized gases orfluids (mediums) may be used in the alternative.

The reduced dimension also facilitates the piston's 32 ability to wobble(cant or tilt) within the cylinder 22 to facilitate the installation andthe removal of the piston 32 from the cylinder 22. See FIG. 4.Preferably, the piston 32 and the cylinder 22 are allowed to wobblerelative to the shock absorber shaft S up to 5 degrees or more throughthe use of highly compliant, flexible shaft seals 28, 38.

FIG. 4 illustrates how the piston 32 of the present invention is able towobble (or cant or tilt) relative to the cylinder 22 during assembly ofthe piston into the cylinder, due in part to: the cylinder not beingdouble-walled, and the piston 32 having a reduced diameter at the top,and having a skirt diameter that is significantly smaller than thediameter of the cylinder bore and/or a removable skirt. FIG. 4demonstrates how the piston-bore seal 40 can pass over the retainingring groove 20 without being parallel to the groove. This greatlyfacilitates the use of seals 40 that have larger sizes and/or otherfeatures, such as over-sized sealing lips and/or wipers that would notbe able to easily pass over the retaining ring groove 20 in the cylinderin a parallel orientation. The ability of the piston to wobble (or cantor tilt) within the cylinder, and to use seals that perform better,greatly improves the operation, durability, and reliability of thelifting apparatus in the present invention.

Without the ability for the piston 32 to wobble (or cant or tilt) withinthe cylinder, the piston-bore seal 40 would become lodged in theretaining ring groove 20 during installation or removal of the piston.The ability to tilt the piston 32 and piston-bore seal 40 out ofparallel alignment with the retaining ring groove 20 allows the piston32 and piston-bore seal 40 to pass over the retaining ring groove 20without becoming lodged or damaged. The ability to wobble or cant thepiston also allows for the use of piston-bore seals 40 with advantageousconfigurations and features, including over-sized upper sealing lips 41and wiper features 42 (both shown in FIG. 5) that provide better sealingcapabilities, clean the cylinder bore every time the piston is activated(when the piston 32 and cylinder 22 slide apart), greatly reduces thewear on the cylinder's bore, and increases the life of the cylinder andthe bore seals. The wobbling (tilting or canting) allows for the use ofsuch seals because without the wobbling, the seals would otherwisebecome lodged in the retaining ring groove 20 resulting in damage to theseals.

Referring to FIG. 1, the piston-bore seal 40 works in conjunction withthe smooth surface of the cylinder bore 18 to form an airtight andexpandable pressure space between the cylinder and the top of thepiston. The retaining ring 72, inserted in the retaining ring groove 20,retains the piston 32 within the cylinder 22 and works in conjunctionwith the piston skirt 62 and upper 56 and lower 58 tapered sections ofthe piston skirt to maintain the alignment of the same relative to thevertical axis of the cylinder 22. The retaining ring 72 also serves as abarrier to keep dust and other contaminants away from the cylinder borewhen the piston is in its retracted (deactivated) position.

The presently preferred embodiment (as described above) providessignificant benefits over the prior art. Referring to FIG. 2, shown is aprior art device that uses a conventional cylinder 12 with an outercylinder bore (wall) 18, an inner cylinder bore (wall) 24 facing thepiston 32, and an inner cylinder bore (wall) 22 facing the shockabsorber shaft S. The inner cylinder bore (wall) 22 facing the shockabsorber shaft S has a larger diameter than the shock absorber shaft S.The diameter of the inner cylinder bore 24 facing the piston 32 must belarge enough to accommodate the thickness of the cylinder wall and anybump stop 10 and/or the shock absorber body B, as well as othercomponent, such as a possible dust sleeve, which may interfere with theoperation of the suspension system. During compression of the coilspring C, the shock absorber body B may move into the space within theinner cylinder bore (wall) 22 and thus the diameter of the innercylinder bore (wall) 22 must be large enough to accommodate the size ofthe shock absorber body B.

Within the outer cylinder bore 18 and the inner cylinder bore 24 thereis a ring shaped piston 32. This piston has inner seal(s) 39 that forman air tight seal against the inner wall 24 and outer seal(s) 40 thatform an airtight seal against the outer cylinder bore 18.

Pressurized fluid or gas is introduced through the inlet port 14 toactivate and press down upon the ring shaped piston 32. The annular areaon the top of the piston 32 between the inner cylinder wall 24 and theouter cylinder wall 18 is the effective pressurized area. It is only inthis area that pressure can be applied to the top of the piston, whichthen presses on the coil springs, to raise the cylinder 12 against theunderbody of the vehicle. The effective pressurized area issubstantially smaller than the effective pressurized area in thepresently preferred embodiment of the invention (as shown in FIG. 1),which results in a lower lifting capacity for the prior art device incomparison to the present invention.

For example, in order to lift a 1,000 pound load on a single liftingdevice, the prior art requires a storage tank that has 8.247 times thecapacity as the storage tank in the present invention. This assumes thecontrolled variables of a shock absorber with a 0.5″ shaft, a cylinderbore with a 4.5 inch inside diameter (ID), piston stroke of 2 inches,tank air pressure at 120 PSI and a lift load of 1,000 pounds on a singlecylinder.

Example of the Present Invention vs Prior Art:

The present invention utilizes the 0.5″ shock absorber shaft as itssealing surface (inner bore) while the prior art uses a 3″ inner bore.It is able to lift 1,000 pounds with a tank size of approximately 0.154Gallons. The prior art requires a tank size of 1.27 Gallons which is824.7% of the present invention required tank size.

The Present Invention Requires a Tank Size of 0.154 Gallons to Lift1,000 Pounds.

-   4.5″ ID of cylinder-   0.5″ Shock Absorber Shaft diameter (serves as the inner bore)-   120 PSI Tank Pressure-   1,000 pounds Lift for a single cylinder-   Tank Size Required: 0.154 Gallons    Prior Art System Requires a Tank Size of 1.270 Gallons to Lift 1,000    Pounds.-   4.5″ ID of cylinder-   3″ Inner bore of a conventional hollow cylinder example-   120 PSI Tank Pressure-   1,000 pounds Lift for a single cylinder-   Tank Size Required: 1.270 Gallons    The Present Invention can Lift 1,702 Pounds with a 1.270 Gallon Tank    Size.-   4.5″ ID-   0.5″ Shock Absorber Shaft diameter (serves as the inner bore)-   120 PSI Tank Pressure-   1,702 pounds Lift for a single cylinder-   Tank Size: 1.27 Gallons

FIGS. 2 and 3 illustrate the inner piston seals 39 and the outer pistonseals 40 in the prior art devices. Due to limited available space forthe seals and the coil spring C, the location, size, and design of theseals are restricted. To avoid interference between the seals and thecoil spring C, the seals may be positioned above the coil spring asshown in FIGS. 2 and 3. As a result, the piston 32 must be thicker toaccommodate the seals, and the top of the coil spring must be relocatedto a lower position than in the present invention. This means that theground clearance of the vehicle will not be as low as could be. Tooffset this raising of the vehicle, the original coil spring C may needto be replaced with a shorter coil spring at an added cost and withreduced performance.

The pistons 32 used in prior art, as shown in FIGS. 2 and 3, are alsorestricted from wobbling (or canting) within the cylinder 12 to preventthe seals 39, 40 from losing contact with the cylinder bore 18 (in FIG.2), and the outer cylinder bore (wall) 18 and an inner cylinder bore(wall) 24 facing the piston 32 (in FIG. 3), which would result in a leakand failure of the lift system. Thus, the pistons 32 are designed to bethick (and tall) enough to prevent excessive wobbling (or canting)within the cylinder. The walls of the cylinder are used to guide thepiston and keep it in alignment with the cylinder. The pistons are alsodesigned to fit more snugly into the cylinders than in the presentinvention. This also prevents the pistons from wobbling excessively.This arrangement makes it difficult or impossible to use seals that maybecome lodged in any grooves in the cylinder wall such the groove 20 forthe retaining ring.

The pistons used in prior art also have outer circumference surfacesthat extend substantially in the longitudinal or axial direction, asillustrated in FIGS. 2 and 3. The length of the outer cylindricalsurface must be long enough to maintain the axial alignment of thepiston in the cylinder bore. In the present invention, illustrated inFIG. 1, the piston 32 uses a piston skirt 62 that is much smaller indiameter than the cylinder bore 18 to help maintain axial alignment ofthe piston 32 relative to the cylinder bore 18. The top sealing sectionof the piston 32 is above the skirt 62 and it is shorter in the axialdirection than the cylindrical outer surface of pistons used in priorart.

In the prior art, shown in FIGS. 2 and 3, the piston 32 cannot travellower than the retaining ring 72, which limits the extension of thepiston. In contrast, the piston skirt 62 in the presently preferredembodiment of the invention, shown in FIG. 1, can easily travel lowerthan the retaining ring 72. This means it has a longer effective strokethan the prior art devices. This longer stroke results in the ability tolift vehicles to a greater height than in prior art with a cylinder ofthe same axial length. Whereas a prior art cylinder would need to belonger to accommodate the thickness of the piston. Most cars, however,have space limitations that restrict the size of the suspension liftingdevice. The present invention uses a device that maximizes the strokelength of the piston within a given cylinder height so that the devicecan be effectively used in vehicles with space limitations.

Referring back to FIG. 1, the top of the coil spring C may extend higherthan the piston-bore seal 40 without interfering with that piston-boreseal 40. This feature significantly reduces the thickness of the pistonthat rests on top of the coil spring C and therefore allows the vehicleto be at a lower ground clearance when the system is not active. Thisreduced thickness of the piston top eliminates or significantly reducesthe need to replace the original coil spring C with a shorter coilspring to maintain proper normal vehicle height. It also significantlyreduces the overall length, weight, and cost of the present invention'scylinder and piston assembly while providing added stroke length for thepiston compared to the prior art shown in FIGS. 2 and 3.

The practical range for the thickness of the piston top in the presentlypreferred embodiment is approximately between 3 to 25 mm. Preferably,the thickness should be approximately in the range of 3 and 10 mm.Optimally, the thickness should be approximately in the range of 3 to 6mm. The prior art as shown in FIGS. 2 and 3 do not provide protectionfrom contamination of the outer cylinder bore (wall) 18, the innercylinder wall 24, the shock absorber shaft S, or the shock absorbershaft seal. There is no practical way to protect all of these surfaceswithout loosing efficiency and/or lifting capability of the system ofthe prior art system shown in FIG. 2. The lack of protection fromcontaminants results in added wear, shorter useful life of thecomponents, lower reliability and higher maintenance costs than in myinvention shown in FIG. 1.

Referring to FIG. 2, it is difficult or impossible to use a dust sleeveto protect the shock absorber shafts from contaminants without reducingthe effective pressurized area to press upon the piston. The innercylinder wall 22 occupies the space that would be needed by a dustsleeve unless the inner cylinder wall 22 was moved further away from theshock absorber shaft S. In order to accommodate the use of a bump stopand a dust sleeve that is large enough to fit over the shock absorberbody B, the prior art's hollow cylinder inner wall surface 22 would needto be large enough to accommodate a dust sleeve within the insidediameter of the cylinder wall. This would greatly reduce the effectivepressurized area over the ring shaped piston 32 and may render thepiston 32 incapable of generating enough lifting force to raise thevehicle.

The seals used in the present invention, shown in FIG. 1, include thecylinder-shaft seal 28, the piston-shaft seal 38, and the piston-boreseal 40. These seals may be made of rubber, urethane or other commonlyused seal materials. They may have a wide range of shapes, includingsimple O-rings, rectangular seals, U seals, and seals with wiperfeatures. FIG. 5 illustrates a cross-sectional view of a presentlypreferred embodiment of a piston-bore seal 40. FIG. 7 illustratescross-sectional view of a presently preferred embodiment thecylinder-shaft seal 28. FIG. 8 illustrates a cross-sectional view of apresently preferred embodiment of the piston-shaft seal 38.

The piston-bore seal 40 in FIG. 5 has an upper sealing lip 41 with anover-sized dimension relative to the cylinder bore. This seal has bettersealing capabilities than a simple seal, as illustrated in FIG. 6,especially if the piston is allowed to wobble (cant or tilt) within thecylinder. A seal with an over-sized upper sealing lip 41 would becomelodged in the retaining ring groove if it were inserted into a cylinderwithout tilting the piston and seal at an angle to the groove. In thepresently preferred embodiment of the invention, the upper sealing lip41 extends between 1 mm to 2 mm above the rest of the seal. At 2 mm, theseal has greater sealing capacity to avoid leaks while the pistonwobbles (cants or tilts) within the cylinder bore. The wiper 42 sectionof the seal in FIG. 5 serves to wipe contaminants from the cylinder borewhen the piston is activated to move downward to raise the vehicle. Thisreduces the amount of contaminants on the cylinder bore that wouldotherwise contact the upper sealing lip 41. By wiping contaminants fromthe cylinder bore, the wiper 42 reduces wear on the bore and seal andprolongs the useful life of these components.

FIG. 6 illustrates a simple seal 44 that is typically used in the priorart devices shown in FIGS. 2 and 3. This type of seal is used because itcan traverse over a groove in the cylinder, such as the retaining ringgroove 20, without becoming lodged in the groove. However, this type ofseal also has a number of shortcomings. As shown in FIG. 3, the simpleseal would not seal well if the piston 32 were to wobble (cant) inrelation to the cylinder bore 18. If the piston 32 were to wobble, thesimple seal would lose contact with the cylinder's bore 18 and the sealwould fail to maintain pressure. To prevent this failure, prior artsystems restrict the wobbling of the pistons in the cylinder. This isaccomplished in various ways, such as the use of double cylinder wallsas illustrated in FIG. 2. The prior art also uses thick cylindricalpiston designs that cannot wobble within the cylinder because of a closetolerance fit to the cylinder bore as shown in FIG. 3.

Another problem with simple seals 44 used in prior art (as illustratedin FIG. 6) is that they allow more contaminants to pass over the seal'ssealing surface resulting in abrasion and damage to the seals and thecylinder bore. This type of seal does not have the ability toeffectively wipe debris or contaminants from the cylinder bore 18 asdoes the seal with the wiper feature 42 illustrated in FIG. 5.

In the prior art, as shown in FIG. 2, the piston 32 is retained inalignment with the cylinder 12 by an outer cylinder bore (wall) 18 andan inner cylinder bore (wall) 24 facing the piston 32. This arrangementdoes not allow the piston to wobble (cant or tilt) once it is installedin the cylinder. This means that the piston seals 39, 40 remain parallelwith any features in the cylinder walls 18, 24, such as the retainingring groove 20, during assembly and dis-assembly of piston with thecylinder. Because the seals 39, 40 will enter and exit the cylinder in aposition that is parallel with the retaining ring groove 20, they wouldtend to become lodged in the groove if they are large enough to do so.This can result in damage to the seals and it prohibits the use of sealswith beneficial features, such as larger sealing lips with greatercompression and/or compliance with the cylinder bore and better scalingcapabilities. An example of a seal with beneficial design features isthe use of wiper feature 42, as illustrated in FIG. 5, to clean thebore(s) and reduce wear of the inner and outer cylinder walls 18, 24 asillustrated in FIG. 2 and the seals 39, 40. Wiper seals would have wiperblades to wipe contaminants from the cylinder walls (bores).

FIG. 10 illustrates another presently preferred embodiment of theinvention. In this embodiment, cylinder 22 has an upper retaining ringgroove 21 and a lower retaining ring groove 20 located at the bottom ofthe cylinder bore 18. An upper retaining ring 70 is located in the upperretaining ring groove 21. A lower retaining ring 72 is located in thelower retaining ring groove 20. A guide ring 71 is located between theupper retaining ring 70 and the lower retaining ring 72. The guide ring71 extends inwardly toward the shock absorber shaft S, farther thaneither the upper retaining ring 70 or lower retaining ring 72, so thatit comes into contact the piston skirt 62 instead of the upper and lowerretaining rings 70, 72. The guide ring 71 is preferably made of Teflonor any other suitable smooth material.

The use of a smooth surfaced (Teflon) guide ring 71 is preferablebecause it is used to guide the piston skirt 62 instead of the hard(metal) retaining rings 70,72. This reduces wear on the piston skirt 62,thus prolonging the life of the piston skirt 62 and reducing repairand/or replacement costs.

FIG. 11 illustrates another presently preferred embodiment of theinvention. The piston 32 has an outer circumferential piston-flange 37downward from the outer circumferential inlet recess 34 at top of thepiston 32 to serve as a positive stop that limits the travel of thepiston 32 in the cylinder 22. The piston 32 preferably has a skirt 62that is smooth and straight (not tapered). A cylinder ring 74 isattached to the bottom of the cylinder side walls through conventionalmethods, including screw threads 75 in the cylinder ring 74 and thebottom of the cylinder 12. The cylinder ring 74 has a cylinder ringflange 76 that extends inward (toward the shock absorber shaft) andserves as a positive stop to limit the travel of the piston 32. Thecylinder ring 74 has a cylinder ring groove 77 to retain a cylinder ringseal 78. The cylinder ring seal 78 forms an air-tight seal between thecylinder ring 74 and the piston skirt 62. The bottom edge of the pistonskirt (at the skirt bottom) has a taper 79 to facilitate the assembly ofthe cylinder ring seal 78 over the bottom edge of the piston 79.

The presently preferred embodiment shown in FIG. 11 utilizes anundersized piston skirt 62 that does not come into contact with thecylinder bore 18. Preventing contact between the cylinder bore 18 andthe piston skirt 62 results in less wear upon the cylinder bore 18 andthe piston skirt 62 resulting in longer life of these parts and lesscost for repairs. This presently preferred embodiment of the inventionalso allows the piston 32 to wobble (cant or tilt) within the cylinderbore 18 until the cylinder ring 74 and the cylinder ring seal 78 areinstalled onto the cylinder 12. Once the cylinder ring 74 and cylinderring seal 78 are installed, they form an air-tight seal with the pistonskirt 62 and maintain adequate alignment of the piston 32 within thecylinder 12.

The cylinder ring 74 may be various lengths to provide a means of easilyaltering the length of the cylinder 12 and cylinder ring 74 assembly.Likewise, the cylinder 12 may be made in various lengths to alter thelength of the cylinder 12 and cylinder ring 74 assembly. By altering thelength of the cylinder 12 and the cylinder ring 74 assembly, the strokeof the piston 32 within the cylinder 12 can altered to achieve anoptimum stroke length.

The cylinder ring 74 may be made in any length and may effectivelyreplace the cylinder side walls. Likewise, the cylinder 12 may be madein any length and may be so short that the cylinder side walls areeffectively replaced by the cylinder ring 74 with adequate length toprovide adequate stroke length for the piston 32.

Activation of the Lifting System, Manual Buttons, Cruise Control Buttonsand Automated Activation

Referring to FIG. 1, in the presently preferred embodiment of theinvention, the piston 32 is activated by the introduction of apressurized fluid, such as compressed air, through the inlet port 14.The pressurized air activates the device by pushing the piston 32downward and the cylinder 12 upward (the piston and cylinder slideapart). The force of the cylinder being pushed upward raises the vehiclewhen the force is great enough to overcome the weight of the vehicle.When the device is deactivated, the pressurized air rushes out of theinlet port 14 and the piston 32 and cylinder 12 return to their restingposition adjacent to each other (the piston and cylinder slidetogether).

FIG. 9 shows a flow diagram of the lift system. First a compressor pump82 generates compressed air that is stored in a storage tank 80. Thecompressed air is released from the storage tank 80 into the cylinderand piston assemblies 88 and 89 through the opening of one or more upvalve(s) 84 to raise the vehicle. To lower the vehicle back to itsnormal state, a down valve 86 is opened to release the air from thecylinder and piston assemblies.

The up valve 84 and the down valve 86 may be activated by various meanssuch as manual switches or controls. In a presently preferredembodiment, an Electronic Control Unit (ECU) 90 is employed. The ECUreceives inputs from various sources such as push button(s) 92, 94, 96and 98, which are controlled by a driver. The push button(s) 92, 94, 96and 98 may be the Original Equipment Manufacturer (OEM) cruise controlbuttons and/or they may be any combination of OEM button(s) orafter-market button(s). The push buttons may also be rocker switches, orpush button type switches or any other type of switch. They may have LEDlights that display one or more colors to indicate status or for basicillumination. The LED lights may be lit constantly or pulsed at variousfrequencies to indicate the status of various functions and/or settings,or to provide feedback to the user when setting parameters to thecontrol system. Additional feedback is optionally provided to the driverthrough audible devices, such as buzzers, which can be varied in theirtone and to indicate such things as the status of the operation of thesystem or confirmation of commands to the system.

The invention may be installed on the front wheels only or on the frontand rear wheels of vehicles. The front and rear devices may be activatedsimultaneously, or independently from each other. They may also beactivated with a delay between the front and rear devices.

Many vehicles have existing OEM cruise control systems with pressbuttons that are located on or near the steering wheel to safelyactivate a vehicle's cruise control system. These buttons can be safelyactivated without the need for a driver to take his eyes off the road tolook for the buttons because they are easily accessible at or near adriver's fingertips. These OEM cruise control systems typically do notoperate at slower vehicle speeds because cruise control systems areintended to be used at highway speeds. Thus, these systems are perfectfor a dual use in connection with the present invention, which is onlyactivated when a vehicle is at a slower speed as it approaches anobstacle in its path.

In the presently preferred embodiment of the invention, the ECU 90 hasan interface that responds to outputs from the OEM cruise controlbuttons 94, 96 and 98 when the OEM cruise control system is not in use.The OEM cruise control buttons are used to perform various functions.For example, the Main switch 92 can be used to turn the vehicle's cruisecontrol functions on or off and to activate or deactivate the liftsystem. When the OEM cruise control system is turned off, the liftsystem is turned on and the output from the Accel button 96 can be used,for example, to activate the lifting of the lift system and the vehicle.The Decel button 98 can be used to initiate the lowering of the liftsystem.

Prior art vehicle lift systems require the operator to take his eyes offthe road so that a driver can look for and press an after-market manualswitch that is added to the vehicle for raising and lowering of thevehicle. The use of the OEM cruise control system interface in thepresent invention provides a convenient and safer method for activatingthe lift system. It also eliminates the need for after-market switch(es)to be installed in the vehicle, which would require additional labor andcosts.

The OEM cruise control system interface also enables the cruise controlbuttons to be used to select and activate other features, for exampleproximity sensors and speed sensors. The proximity sensors may beultrasonic sensors, infrared sensors, capacitive discharge sensors orany other type of sensor that can measure the proximity of the vehicleto the road surface or obstacles, such as speed bumps, that are underthe vehicle. They can be installed under the vehicle in one or morelocations. The proximity sensors are preferably adjusted or calibratedto activate the ECU and the lift system at the desired distances fromobstacles. When a signal from the proximity sensor(s) to the ECUindicates that the sensor is closer to an obstacle than desired, the ECUactivates the up valve 84 to raise the vehicle away from the obstacle.The ECU uses various parameters, such as time and proximity, to checkfor the presence of obstacles, and automatically lowers the vehicle tothe normal state when the desired conditions are met. The ECU may alsoreceive input signals from a vehicle speed sensor. The ECU may use suchinformation to control or limit the raising and/or lowering of thevehicle depending on the speed of the vehicle.

The ECU 90 may be programmed in a variety of ways. For example, the ECU90 can be programed directly through the use of the push button(s) 92and cruise control buttons 94, 96 and 98. It can also be configuredthrough the use of a computer connected to the ECU and/or through theuse of DIP switches, portable flash drives or other devices. The ECU 90may also be programmed to modify its response to inputs (adjustment)regarding time durations for the activation of the up valve and downvalve; delay time for the starting of the compressor pump upon startingthe vehicle; duration for the vehicle to remain in the lifted positionprior to activating the lowering of the vehicle; proximity distancesettings for the automatic activation of the lifting and lowering of thevehicle; sensitivity and speed settings for the input signals from theproximity sensor(s); vehicle speed settings for various functions suchas for limiting the lifting of the vehicle and for the automatedlowering of the vehicle if excessive vehicle speed is detected. Thesetypes of parameters may be programmed into the ECU 90 and/or the usermay select or adjust the parameters affecting the ECU 90 and itsoperation of the invention.

While the present invention has been disclosed in connection with thepresently preferred embodiments described herein, it should beunderstood that there may be other embodiments which fall within thisspirit and scope of the invention as defined by the claims. Accordingly,no limitations are to be implied or inferred in this invention except asspecifically and as explicitly set forth in the claims.

Industrial Applicability

This invention can be used whenever it is necessary to lift a vehicle toavoid a collision with an obstacle in the vehicle's path.

I claim:
 1. A device for lifting and lowering a vehicle with asuspension system having a coil spring and shock absorber with a shockabsorber shaft and a shock absorber body, wherein said coil spring has acoil spring diameter and is coaxially coiled around said shock absorbershaft, comprising: a hollow cylinder having a cylinder inner diameterlarger than said coil spring diameter, having a cylinder top with acentral cylinder shaft aperture, cylinder side walls connected to andextending downwardly from said cylinder top to a cylinder bottom,wherein said cylinder side walls define a cylinder bore having saidcylinder inner diameter, and an inlet port extending inwardly throughsaid cylinder side walls or said cylinder top, wherein said cylinder issealingly coaxially mounted onto said shock absorber shaft through saidcylinder-shaft aperture; a piston having a substantially circular pistontop with a central piston-shaft aperture and a circumferentialpiston-bore groove, said piston top having a reduced diameter to allowsaid piston top to tilt at least 5 degrees within said cylinder borewhen said piston top is being inserted into said cylinder bore, wherebysaid piston top can be inserted into said cylinder bore in anorientation tilted by at least 5 degrees to facilitate insertion of saidpiston top into said cylinder bore, said piston top sealingly coaxiallymounted onto said shock absorber shaft through said piston-shaftaperture to be slidable within said cylinder bore and to receive saidcoil spring; a piston-bore seal retained in said piston-bore groove toform a seal between said piston and said cylinder bore; whereby saidpiston top, said cylinder top, said cylinder side walls and saidpiston-bore seal form a sealed expandable pressure space that is influid communication with said inlet port; whereby said device isactivated when a pressurized fluid enters through said inlet port intosaid expandable pressure space and causes said piston and said cylinderto slide apart, thereby raising said vehicle, and deactivated when saidpressurized fluid exits through said inlet port from said expandablepressure space and causes said piston and said cylinder to slidetogether, thereby lowering said vehicle.
 2. A device according to claim1, further comprising: a substantially cylindrical piston skirtextending downwardly from said piston top to a piston skirt bottom,having a skirt diameter sufficiently less than said cylinder innerdiameter whereby said piston top can tilt at least 5 degrees within saidcylinder bore when said piston top is being inserted into said cylinderbore.
 3. A device according to claim 2, further comprising: asubstantially circular bottom flange extending outwardly from saidpiston skirt bottom; whereby said bottom flange creates a barrierbetween said piston skirt and said cylinder bore to prevent contaminantsfrom entering into said cylinder bore.
 4. A device according to claim 2,wherein said cylinder bottom has a circumferential retaining ringgroove, further comprising; a retaining ring in said retaining ringgroove; whereby said retaining ring limits tilting of said piston aftersaid piston has been installed in said cylinder; and whereby saidretaining ring creates a barrier between said piston skirt and saidcylinder bore to prevent contaminants from entering into said cylinderbore.
 5. A device for lifting and lowering a vehicle with a suspensionsystem having a coil spring and shock absorber with a shock absorbershaft and a shock absorber body, wherein said coil spring has a coilspring diameter and is coaxially coiled around said shock absorbershaft, comprising: a hollow cylinder having a cylinder inner diameterlarger than said coil spring diameter, having a cylinder top with acentral cylinder shaft aperture, cylinder side walls connected to andextending downwardly from said cylinder top to a cylinder bottom,wherein said cylinder side walls define a cylinder bore having saidcylinder inner diameter, and an inlet port extending inwardly throughsaid cylinder side walls or said cylinder top, wherein said cylinder issealingly coaxially mounted onto said shock absorber shaft through saidcylinder-shaft aperture; a cylinder ring attached to said cylinderbottom having a cylinder ring groove and an inwardly extending cylinderring flange; a piston having a substantially circular piston top with acentral piston-shaft aperture, said piston top having a reduced diameterto allow said piston top to tilt at least 5 degrees within said cylinderbore when said piston top is being inserted into said cylinder bore, acircumferential piston flange extending outwardly from said piston tophaving a diameter less than said cylinder inner diameter, whereby saidpiston top can be inserted into said cylinder bore in an orientationtilted by at least 5 degrees when said piston top is being inserted intosaid cylinder bore, said piston top sealingly coaxially mounted ontosaid shock absorber shaft through said piston-shaft aperture to beslidable within said cylinder bore and to receive said coil spring; asubstantially cylindrical piston skirt extending downwardly from saidpiston top, having a skirt diameter sufficiently less than said cylinderinner diameter whereby said piston top can tilt at least 5 degreeswithin said cylinder bore when said piston top is being inserted intosaid cylinder bore; a cylinder ring seal mounted in said cylinder ringgroove to form a seal between said cylinder ring and said piston skirt;whereby said piston top, said piston skirt, said cylinder top, saidcylinder side walls and said cylinder ring seal form a sealed expandablepressure space that is in fluid communication with said inlet port;wherein said cylinder ring flange limits travel of said piston flangewithin said cylinder; whereby said device is activated when apressurized fluid enters through said inlet port into said expandablepressure space and causes said piston and said cylinder to slide apart,thereby raising said vehicle, and deactivated when said pressurizedfluid exits through said inlet port from said expandable pressure spaceand causes said piston and said cylinder to slide together, therebylowering said vehicle.
 6. A device according to claim 1 or 5, furthercomprising a cylindrical coil spring flange extending downwardly fromsaid piston top to retain said coil spring in said piston.
 7. A deviceaccording to claim 6, further comprising a bump stop flange extendinginwardly from said coil spring flange; and a bump stop retained on saidbump stop flange.
 8. A device according to claim 2 or 5, wherein saidpiston and said piston skirt are integrally formed.
 9. A deviceaccording to claim 1, further comprising a wiper mounted on said pistonto clean said cylinder bore when said cylinder and said piston slideapart.
 10. A device according to claim 5, further comprising a wipermounted on said cylinder ring to clean said piston skirt when saidcylinder and said piston slide together.
 11. A device according to claim1 or 5, wherein said vehicle has cruise control buttons, furthercomprising: an electronic control unit mounted in said vehicle operablyconnected to said device and controllably connected to said cruisecontrol buttons; whereby said buttons activate, deactivate and controlsaid device.
 12. A device according to claim 1 or 5, further comprising:an electronic control unit mounted in said vehicle operably connected tosaid device; and a proximity sensor operably connected to saidelectronic control unit for sensing of said vehicle's ground clearance.13. A device according to claim 1 or 5, further comprising: anelectronic control unit mounted in said vehicle operably connected tosaid device; and a speed sensor operably connected to said electroniccontrol unit for sensing of said vehicle's speed.
 14. A device accordingto claim 1 or 5, further comprising: an electronic control unit mountedin said vehicle operably connected to said device; a proximity sensoroperably connected to said electronic control unit for sensing of saidvehicle's ground clearance; and a speed sensor operably connected tosaid electronic control unit for sensing of said vehicle's speed.
 15. Adevice according to claim 11, further comprising: a speed sensoroperably connected to said electronic control unit for sensing of saidvehicle's speed.
 16. A device according to claim 11, further comprising:a proximity sensor operably connected to said electronic control unitfor sensing of said vehicle's ground clearance; and a speed sensoroperably connected to said electronic control unit for sensing of saidvehicle's speed.
 17. A device according to claim 1 or 5, wherein saidpressurized fluid is pressurized air.
 18. A device for adjusting groundclearance of a vehicle having cruise control buttons, comprising: anelectronic control unit mounted in said vehicle controllably connectedto said cruise control buttons, whereby said cruise control buttonscontrol said electronic control unit; a vehicle lift system to lift saidvehicle to adjust said ground clearance operably connected to saidelectronic control unit, whereby said electronic control unit operatessaid vehicle lift system; whereby said electronic control unit activatesand deactivates said vehicle lift system to lift and lower said vehiclewhen said cruise control buttons are pressed.
 19. A device according toclaim 18, further comprising a vehicle speed sensor operably connectedto said electronic control unit; wherein said electronic control unitdoes not activate said vehicle lift system if said speed sensor sensesexcessive speed of said vehicle; and wherein said electronic controlunit deactivates said vehicle lift system to lower said vehicle if saidspeed sensor senses excessive speed of said vehicle.
 20. A device foraccording to claim 18, wherein said electronic control unit isprogrammable to control duration of activation and deactivation of saidvehicle lift system.
 21. A device for automatically adjusting the groundclearance of a vehicle comprising: an electronic control unit mounted insaid vehicle; a proximity sensor mounted under said vehicle and operablyconnected to said electronic control unit to monitor distance betweensaid vehicle and obstacles on a road surface; a vehicle speed sensormounted in said vehicle and operably connected to said electroniccontrol unit to sense excessive speed of said vehicle; a vehicle liftsystem to lift and lower said vehicle to adjust said ground clearanceoperably connected to said electronic control unit; whereby saidelectronic control unit automatically activates said vehicle lift systemto lift said vehicle when said proximity sensor senses less than adesired ground clearance between said vehicle and said obstacles;whereby said electronic control unit automatically deactivates saidvehicle lift system to lower said vehicle when said proximity sensorsenses greater than said desired ground clearance between said vehicleand said obstacles; and whereby said electronic control unit preventsactivation of said vehicle lift system to raise said vehicle if saidspeed sensor senses excessive speed of said vehicle; and whereby saidelectronic control unit deactivates said vehicle lift system to lowersaid vehicle if said speed sensor senses excessive speed of saidvehicle.
 22. A device according to claim 21, wherein said electroniccontrol unit is controllably connected to cruise control buttons.
 23. Adevice according to claim 22, wherein said cruise control buttons allowa user to calibrate said proximity sensor for activation at variousdesirable ground clearances, and to calibrate said speed sensor forsensing various excessive speeds.
 24. A device according to claim 21,wherein said electronic control unit is programmable to controlactivation and deactivation of said vehicle lift system.